This invention relates to a shuttle mechanism for a machine tool, and more particularly to an improved rotary shuttle mechanism for a machine tool which can exchange workpieces between a shuttle and an operating station without the requirement of a power mechanism for moving the pallet between the workpiece support and an indexing table for the operating station.
Representative of shuttle mechanisms or pallet transfer systems are those disclosed in the following U.S. Pat. Nos. 3,825,245 entitled Workpiece Changer Mechanism For A Machine Tool, issued July 23, 1974; 3,986,617 entitled Indexing Pallet Carrier For Machine Tools, issued Oct. 19, 1976; and 4,373,840 entitled Pallet Transfer System, issued Feb. 15, 1983. In all of the shuttle mechanisms disclosed in these patents for transferring a workpiece from a workpiece storage support to an indexing table in conjunction with a machine tool center, there is some sort of power mechanism for moving the workpiece on a pallet off of the workpiece support and on to the indexing table. For example, this is illustrated in U.S. Pat. No. 3,825,245 by a cylinder (61) which is actuated to effect movement of a piston rod (59) for purposes of moving a latch (91) into an outward engaged position with a pallet (30). An indexing table then releases pallet (30) by urging it upwardly into clamped engagement with latch 91 of the outwardly extending piston rod (59) which is then retracted to move the latched pallet (30) into parked storage station 47a. In U.S. Pat. No. 3,986,617, a bi-directional rotary hydraulic motor (98) which is connected to a shaft (99) and extends entirely across the pallet changer drives the rails (85) through a conventional rack and pinion mechanism for a similar purpose. A clamp-type brake (100) which is normally spring urged into gripping engagement with a shaft (99) is employed to lock the rails in place except when a pallet change is to be made. In U.S. Pat. No. 4,373,840 a reciprocal latch device (85) is provided to draw a pallet (82) on to a ram (81) and over guide ways (120 and 121). The reciprocating latch motion is effected by a ball screw (125) which can be rotated through appropriate gearing (126) by hydraulic motor (127) or other means.
In addition to eliminating mechanisms in the shuttle for the transfer of the workpiece from the workpiece support to the indexing table, it should be pointed out that rotary shuttles of the type described herein normally require more floor space than a linear shuttle. However, in the rotary shuttle of the present invention, less floor space is required.
It is an advantage of the present invention to provide an improved shuttle mechanism for a machine tool which eliminates the need for a power mechanism to move the workpiece from the workpiece support and on to the indexing table.
It is yet another advantage of the invention to provide improved shuttle mechanisms which require a minimum amount of space and are easily accommodated by the indexing table of the machine tool center.